Engine fan won’t shut off!

Hi guys, looking for some advise again. I have a 2011 International 9900 with a CM871 ISX. Truck was parked a few months and after finishing a full service, the engine fan won’t shut off. I’ve checked coolant sensor, fan solenoid (which only shows 11.3volts), air is reaching fan hub and it locks when disconnecting solenoid connector. Many people say a/c high pressure switch, both the high and low are located just below the passenger seat, outside above steps. When I took plastic cover off to expose high/low switches, the wiring has me baffled! The high and low switches are connected together, with a third separate set of wires running through the floorboards to the evaporator under the passenger seat? Question is... how in hell are the pressure switches receiving power? Or did someone hook the connectors backwards?

 

Yes, I have APADS and neither green or red lights are on. I did the 4x on/off reset, still nothing is on.

 

When it’s aired up, I can hear clutch disengage and spin fan manually, when disconnecting connector at the fan solenoid. Testing voltage at solenoid reads 11.3volts.

 

Exactly what you said. There’s 12.8volts with key on at red wire. Grounded tan wire which only read 5.8volts to frame, about 1 min later fan shut off.

 

What now? Bad APADS?

 

Thanks again HeavyD. You’re the man!